The Conservative party has highlighted how this was contradicted just weeks later by Labour's own manifesto, which said in the small print (sic):

Raising the headline rate to 21% from 2018-19, 24% from 2019-20 and £26% from 2020-21. Small Profits (below £300,000) rate is 20% from 2018-19 and 21% from 2020-21 ‘Ready Reckoner’ includes behavioural change 2013 Ready Reckoner for assumptions on relationship between headline and small profits rate

Currently all companies pay a corporation tax rate of 19 per cent.

The Tories argue this pledge would have involved "hiking taxes on over a million small businesses, risking job losses, lower wages, and local businesses closing".

“Labour’s policies are crumbling before our eyes – it’s clear that their plans would make people’s lives a nightmare with higher taxes, lower wages and fewer jobs. Whilst the Conservatives are getting on with the job of building a stronger economy and a better country for future generations.”